一种高效无污染合成丙酮酸乙酯的新方法

研究了由次氯酸钠和溴化钠催化氧化乳酸乙酯合成丙酮酸乙酯新工艺。并通过正交试验设计方法 ,得出最佳实验操作条件 :温度为 30℃以下 ,反应时间为 8h ,溴化钠与乳酸乙酯的摩尔比为 1∶2 ,盐酸与溴化钠的摩尔比为1∶1. 4,不采用光照 ,并由此得到丙酮酸乙酯最好收率为 82 . 86 %(文献值为 80 . 2 %) ,乳酸乙酯的转化率为10 0 %。     

尿素醇解法合成氨基甲酸乙酯的研究

对尿素醇解法合成氨基甲酸乙酯工艺进行了系统地研究,全面考察了反应温度、原料配比、反应时间及搅拌速度等因素对反应性能的影响。研究发现在反应温度为140℃,乙醇与尿素的摩尔比为4∶1,反应3.5 h,氨基甲酸乙酯最高收率为79.2%。     

含水混酸的酯化分离试验

基于中国石化扬子石化公司化工厂醋酸装置产生大量的含水甲酸、乙酸副产品,通过试验将含水混酸进行酯化、分离,得到符合工业品规格的甲酸乙酯、乙酸乙脂。试验确定酯化塔回流比为3∶1,乙醇分批次加入,乙醇实际投入量与理论量的比为1.2。酯化分离结果:甲酸乙酯的单程收率89.5%,纯度大于97%,乙酸乙酯的单程收率80.1%,纯度大于97%。     

Electrochemical insertion of sodium into hard carbons

The electrochemical insertion of sodium ions into different types of hard carbons was achieved in electrolytes composed of ethylene carbonate as the solvent and NaClO₄ as the salt. For all the materials studied the sodium uptake increases when the carbon highest heat treatment temperature (HTT) decreases. PAN-based carbon fibres appear to be suitable structures to allow significant sodium insertion. Thus, T650 ex-PAN fibres lead to a reversible capacity close to 209 mAh g⁻¹. In that case, sodium insertion occurs in two main ways: one is the adsorption on the single graphene layers and the other is the concomitant insertion into the porosity that occurs below 0.1 V versus Na⁺/Na. This second mechanism, which is indicated by a low-voltage plateau on the electrochemical curves, allows significant insertion. The compared electrochemical study of two saccharose-coke samples corresponding to different regions of Dahn's classification underlines the importance of the carbon precursor and of the manufacture process. The reversible capacity is equal to 184 mAh g⁻¹ for the sample heat treated at 800 °C which presents a high hydrogen content whereas it is close to 145 mAh g⁻¹ for the one characterized by a HTT of about 1500 °C and a low hydrogen content. The best electrochemical performances are obtained for pyrolyzed cellulose carbons. Indeed, the reversible capacity is about 279 mAh g⁻¹. Outgassing these carbons at 950 °C results in such a decrease of the reversible capacity down to 145 mAh g⁻¹. That can be related either to the thermal elimination of heteroelements or to modifications of the pore size distribution. Consequently, the most suitable hard carbon material for anodic applications in rechargeable sodium-ion batteries should both present a high residual hydrogen content and a significant microporosity.     

2-乙基-2- 唑啉的阳离子开环聚合及聚合物的表征

以对甲苯磺酸甲酯为引发剂进行２乙基２唑啉阳离子开环聚合研究，主要考察了不同的单体／引发剂配比、聚合温度和聚合时间对聚合转化率和聚合物分子量的影响。聚合物通过ＩＲ、１Ｈ核磁共振、ＤＳＣ进行表征，并考察了聚（２乙基２唑啉）与部分聚合物和共聚物的共混性能。     

Premodification of Pt/γAl2O3 with Cinchonidine for the Enantioselective Hydrogenation of Ethyl Pyruvate: Effect of Premodification Conditions on Reaction Rate and Enantioselection

The premodification of a 5 wt% Pt/-Al₂O₃ catalyst with cinchonidine (0.01 and 0.2 g g^-1 _catalyst) is described and discussed. Premodification is carried out by treating the catalyst with a solution of cinchonidine followed by solvent removal. Catalysts premodified in this way give the same ee and initial rate of reaction for the enantioselective hydrogenation of ethyl pyruvate as those using the standard in situ modification procedure. Investigations of different solvents for premodification and reaction (dichloromethane, ethanol) show that it is the solvent used for the reaction that controls the observed enantioselection. Premodified catalysts also display the initial transient behavior typically observed with in situ modified catalysts in which the ee increases with conversion in the early part of the reaction. Premodified catalysts show an enhanced rate of reaction when ethanol is used as the reaction solvent compared with in situ modified catalysts under the same conditions. Premodification using aerobic conditions gives the best results and premodified catalysts can be stored prior to use for up to a week without loss of catalytic performance.     

合成氢化松香乙酯的新工艺研究

以DRC为催化剂,在无溶剂条件下,通过氢化松香与乙醇的直接酯化反应合成氢化松香乙酯。探索了反应温度、催化剂用量、反应时间、物料配比等因素对反应酯化率的影响,确定最佳反应条件为:反应温度180℃,催化剂用量为原料氢化松香质量的6%,反应时间6h,醇与酸的摩尔比为3∶1。在最佳条件下酯化率达92.2%。还探讨了用阴离子交换树脂柱层析分离纯化氢化松香乙酯粗产物的方法。此外,利用红外光谱对氢化松香乙酯精制产物进行了表征;用GC-MS分别对氢化松香乙酯粗产物及其精制产物进行了定性和定量分析,比较了柱层析前后化学组成的变化。     

氧化纤维素的制备研究

介绍了氧化纤维素 (DAC)的制备过程 ,用正交法探讨了以NaIO4 作氧化纤维素时反应温度、溶液pH值、氧化剂浓度、反应时间以及交互作用对DAC醛基含量的影响 ,找到了影响醛基含量的主要因素为反应温度、反应温度与NaIO4 的交互作用、反应温度与溶液 pH值的交互作用。初步确定了制备氧化纤维素的反应工艺 ,使醛基含量较高时的最佳反应条件为 :反应温度 3 5℃ ,反应时间 3h ,NaIO4 质量分数 6.78% ,pH值为 2时 ,醛基含量达 68.2 0 %。     

纤维素衍生物液晶相转变和织态结构

本文综述了纤维素衍生物液晶态相转变和织态结构。描述了纤维素衍生物从各向同性态向液晶态的转变过程和液晶态的织构特征。讨论了溶液浓度和温度对液晶相织构的影响。探讨了各种因素,如溶剂、取代基含量、外加力场和外加磁场等对液晶相的形成及织态结构的影响。     

固体超强酸催化合成对羟基苯甲酸乙酯的研究

以固体超强酸ＳＯ４２－／ＴｉＯ２为催化剂，４Ａ分子筛作脱水剂，合成了对羟基苯甲酸乙酯。应用该方法，酯化反应产率高达８４％，同时对影响产率的诸因素进行了考察，其最佳反应条件为：醇酸摩尔比４∶１，催化剂用量９％，反应时间３ｈ，反应温度１１５～１３５℃。